If I use caffeine to improve my performance, how much should I use?
Caffeine in moderate doses can boost both physical and mental performance. It can help maintain alertness when you are doing long, boring activities such as highway driving. It can really help alertness and mental performance when you are sleep deprived. However, if you can, it is better to get the sleep your body needs. The suggested amount to help mental performance is relatively low—one or two cups of coffee (about 80-200 mg of caffeine). Larger doses can cause side effects (such as nervousness, irritability, shakiness, and trouble sleeping). It’s very important not to consume large amounts of caffeine before trying to sleep. Blood levels of caffeine peak at about 60 minutes and last for two to three hours. That also means another dose after four hours might help when you need to stay alert or active for long times. But remember, more caffeine will not improve your performance and the various negative side effects of higher doses might actually make it worse.
FAQ updated 10 May 2014